A round design is the main feature of this Master Sweep chimney brush. The brush is twelve inches in diameter and is perfect for round chimney flues. This 12 Inch Diameter Round Master Sweep Flat Wire Brush Head features a NPT type connector with a 3/8 Inch type thread. The flat bristles are tough on durable and perfect for scoring the baked on and glazed on creosote for faster and more efficient use of creosote cleaning solution.